Conventionally, resin sashes that are excellent in terms of heat insulating and soundproofing properties have been widespread mainly in cold climates, instead of aluminum sashes having bodies formed with aluminum. Such resin sashes are excellent in terms of heat insulating properties, resulting in less dew condensation. Therefore, habitability can be improved.
However, such resin sashes are inferior in terms of fireproof performance, so that they have not been usable for fireproof doors or windows used in fire zones, quasi-fire zones, or the like.
Thus, a sash member described in Patent document 1 below was invented.
The sash member comprises a synthetic resin body that has at least two hollows, the cross-sectional shape of which is substantially rectangular. The hollows are horizontally disposed in the interior and the exterior directions and the neighboring hollows overlap each other across at least half of the region thereof. The sash member further comprises rolled steel members loaded into the hollows and fireproof material loaded into the hollows. In such a constitution, the rolled steel members comprise the center wall portion that extends along the substantially central part between the interior and the exterior surfaces of the hollows and a flange wall portion that extends from both edges of the center wall portion to the interior and the exterior surfaces, and the fireproof material is disposed along the interior and exterior of the central wall portion of the rolled steel members.
Patent document 1: Japanese Patent Publication (Kokoku) No. 6-89622 B (1994)
However, regarding the structure of the sash member described in Patent document 1 above, the hollows, into which the rolled steel member and the fireproof material are loaded, overlap each other across at least half of the region thereof so as to prevent deterioration of fireproof performance resulting from destruction of resin portions by fire. Thus, such sash member is required to have a specific structure for fire protection. In addition, the rolled steel member and the fireproof material that are loaded into all hollows cause increase in the weight of the sash, resulting in problems such as handling difficulties upon production and construction and sensations of massiveness when opening and closing a movable type sash. Further, since the rolled steel member needs to be loaded into all hollows and the fireproof material needs to be applied to the interior and exterior surfaces of the rolled steel member, the operation upon production of the sash becomes complicated and time-consuming. In addition, the rolled steel member is loaded into hollows substantially without leaving a gap therein, so that dew condensation is generated inside of the resin sash due to a heat bridge. Consequently, the rolled steel member tends to become corroded.
The present invention has been made in view of the above problems. The object of the present invention is to provide a fireproof resin sash regarding which fireproof performance is easily imparted to a general resin sash without modification of the structure thereof, such sash being usable in fire zones or the like. Another object of the present invention is to provide a fireproof resin sash that is lightweight and excellent in terms of handleability, so that a simplified production process and cost reduction can be achieved. Further, an object of the present invention is to provide a fireproof resin sash that can immediately provide fireproof performance by preventing penetration in hollows in the event of an outbreak of fire. Furthermore, an object of the present invention is to provide a fireproof resin sash that can prevent corrosion of rolled steel members used therein.